Study On The Accessibility Of Park Green Space For The Elderly In Handan Under The Background Of Spatio-Temporal Changes

In order to study the uniqueness and problems of the demand for urban park green space by the elderly in the context of the increasing population ageing problems and the uneven distribution of urban park green space,the spatial-temporal response relationship between the distribution of the elderly population and the accessibility of the park green space was analyzed.Based on Handan’s 2010 and 2020 population censuses of the elderly in the streets and the corresponding year’s park green data,the Comprehensive Ageing Index(CAI)of the population study was introduced to provide a more comprehensive analysis of the spatiotemporal changes of street population ageing in the study area.The elderly population in the street is then distributed in proportion to the number of households in each neighborhood,taking into account the cost of time and the proportion of the elderly,using Open Street Map(OSM)road network data,Amap bus route planning and improved Gaussian two-step floating catchment area method(GA2SFCA),the accessibility of green space in parks for the elderly in different years and different travel modes was analyzed,the spatial-temporal correlation between the changes of population ageing and the accessibility of the green space in the park for the elderly was analyzed.The results showed that:(1)the Comprehensive Aging Index combined the number,proportion and density of the elderly population to provide a more comprehensive measure of population ageing in the study area;A comparison of street population ageing in the study area between 2010 and 2020 using the Composite Ageing Index showed a clear trend of population ageing deepening in the study area between 2010 and 2020,the number of high comprehensive aging streets is obviously increasing and there is a certain diffusion trend in space.The aging trend of streets is also obvious.(2)under different modes of transportation,the accessibility of the park green space of the elderly is quite different.The mean and standard deviation of the accessibility of the same type of park green space under different modes of transportation vary greatly,there is also a significant difference in the number of high-and low-value settlements for standardized accessibility.In order to improve the convenience of the old people to use the park green space,the optimization of the low accessible area should be emphasized in the traffic planning,increase the density of bus lines.(3)the supply of park green space is obviously increased,but there is obvious spatial dislocation between the supply of park green space and the demand of the aged.From 2010 to 2020,more park green space was added in and around the study area,the mean value of the accessibility of the green space of the elderly park increased from 4.26 m~2/person in 2010 to 8.93 m~2/person in 2020,but the spatial differentiation of the accessibility became more obvious,the standard deviation increased from 9.16 in 2010 to 19.97 in 2020.The high standard deviation means that the spatial distribution of the accessibility value is not uniform,and the accessibility of some regions is obviously higher,by comparing the changes in accessibility and the Composite Ageing Index between high-accessibility and high-ageing areas and streets,the high-value areas of the accessibility of the green space in the study area were not consistent with the high-value areas of the population ageing.The population ageing degree of most of the high-accessibility areas was not outstanding in the study area,both of them have obvious dislocation in space.Based on the above research results,this thesis extracted the residential areas with lower accessibility and more serious population ageing in the elderly park by combining the accessibility of the green space in the elderly park and the population ageing of the streets,on the basis of formulating the relevant optimization principles and strategies,firstly,the quantity of the new park green space is determined by using the K-means clustering algorithm,subsequently,the coordinates of the proposed new park green space were calculated based on the Particle Swarm Optimization data,and the location coordinates of the proposed new park green space were optimized according to the actual situation,it is hoped to provide a reference for the rational layout of urban park green space under the population ageing background.